U.S. patent application number 13/032318 was filed with the patent office on 2011-06-16 for use of a pde 5 inhibitor for treating and preventing hypopigmentary disorders.
Invention is credited to Heidemarie PEUKER.
Application Number | 20110142956 13/032318 |
Document ID | / |
Family ID | 34972435 |
Filed Date | 2011-06-16 |
United States Patent
Application |
20110142956 |
Kind Code |
A1 |
PEUKER; Heidemarie |
June 16, 2011 |
USE OF A PDE 5 INHIBITOR FOR TREATING AND PREVENTING HYPOPIGMENTARY
DISORDERS
Abstract
The invention relates to the use of PDE5 inhibitors for treating
and/or preventing hypopigmentary disorders.
Inventors: |
PEUKER; Heidemarie;
(Penzberg, DE) |
Family ID: |
34972435 |
Appl. No.: |
13/032318 |
Filed: |
February 22, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11660351 |
Jul 5, 2007 |
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PCT/EP2005/007747 |
Jul 15, 2005 |
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13032318 |
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60603069 |
Aug 19, 2004 |
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Current U.S.
Class: |
424/583 ;
424/638; 424/752; 514/171; 514/20.5; 514/250; 514/90 |
Current CPC
Class: |
A61K 38/13 20130101;
A61K 31/519 20130101; A61K 31/00 20130101; A61K 31/436 20130101;
A61K 31/4985 20130101; A61K 2300/00 20130101; A61K 31/519 20130101;
A61K 2300/00 20130101; A61K 2300/00 20130101; A61P 17/00 20180101;
A61K 2300/00 20130101; A61K 31/436 20130101; A61K 31/4985 20130101;
A61K 38/13 20130101 |
Class at
Publication: |
424/583 ;
514/250; 514/20.5; 514/90; 424/638; 514/171; 424/752 |
International
Class: |
A61K 35/50 20060101
A61K035/50; A61K 31/4985 20060101 A61K031/4985; A61K 38/13 20060101
A61K038/13; A61K 31/675 20060101 A61K031/675; A61K 33/34 20060101
A61K033/34; A61K 31/56 20060101 A61K031/56; A61K 31/57 20060101
A61K031/57; A61K 31/573 20060101 A61K031/573 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 19, 2004 |
EP |
04019695.8 |
Claims
1. A method of treating hypopigmentary diseases or disorders
comprising administering a PDE5 inhibitor to a patient suffering
from a hypopigmentary disease or disorder, wherein said PDE5
inhibitor is selected from tadalafil and pharmaceutically
acceptable salts thereof, and wherein said hypopigmentary disease
or disorder is vitiligo.
2. The method according to claim 1, wherein said PDE5 inhibitor is
a compound according to formula (II): ##STR00024## or an isomer
thereof, or a pharmaceutically acceptable salt thereof.
3. The method according to claim 1, further comprising
administering said PDE5 inhibitor topically or systemically or via
a combination thereof.
4. The method according to claim 3, further comprising
administering said PDE5 inhibitor in the form of a medicament that
is in the form of an ointment, a gel, a plaster, an emulsion, a
lotion, a foam, a cream of a mixed phase or amphiphilic emulsion
system, a liposome, a transfersome, a paste or a powder, or a
solution or suspension.
5. A composition comprising tadalafil or a pharmaceutically
acceptable salt thereof and one or more further active ingredients
suitable for the treatment and/or prevention of hypopigmentary
disorders.
6. The composition according to claim 5, further comprising at
least one active ingredient selected from the group consisting of
cyclosporin A, cyclosporin G, cyclosporin B, cyclosporin C,
cyclosporin D, dihydro-cyclosporin D, cyclosporin E, cyclosporin F,
cyclosporin H, cyclosporin I, ASM-240, pimecrolimus, tacrolimus,
13-desmethyl-derivatives of tacrolimus (L-685487), L-683519 and/or
17-ethyl-derivatives of tacrolimus; steroids; vitamin D analogues;
pseudocatalase; levamisole, fluorouracil; alpha-MSH; clofazimine;
thiambutosine BP; chloroquine; penicillamine; tar; minoxidil;
inosiplex; mechlorethamine; cyclophosphamide; anapsos;
antioxidants; pentoxifylline; vitamins and trace elements. vitamin
B12, folic acid, vitamin C, vitamin E, copper salts, human
placental extract, khellin and phenylalanine.
7. The composition according to claim 5, wherein said composition
is formulated for topical use.
8. The composition according to claim 6 wherein said
17-ethyl-derivatives of tacrolimus comprises pimecrolimus,
tacrolimus, or cyclosporin A.
9. The composition according to claim 6 wherein said steroids
comprises betamethasone, betamethasone-17-valerate, fluocinolone,
triamcinolone, triamcinolone acetonide, clobetasol, clobetasol
propionate, halobetasol, hydrocortisone, cortisone, desonide,
prednisolone, paramethasone, methylprednisolone, dexamethasone or
deflazacort.
10. The composition according to claim 6 wherein said vitamin D
analogues comprises calcipotriol.
11. The composition according to claim 6 wherein said antioxidants
comprises Gingko biloba, canthaxanthine, beta-carotene,
alpha-tocopherol, a combination of alpha-tocopherol ubiquinone
seleno-methionine or methionine.
12. The composition according to claim 6 wherein said vitamins or
trace elements comprises vitamin B12, folic acid, vitamin C,
vitamin E, copper salts, human placental extract, khellin and
phenylalanine.
13. A method of treating or preventing hypopigmentary disorders
comprising administering a composition according to claim 5 to a
patient suffering from a hypopigmentary disorder.
Description
CROSS REFERENCE TO PRIOR APPLICATION
[0001] The present application is a divisional of U.S. patent
application Ser. No. 11/660,351, filed Jul. 5, 2007, which is a
national phase application of International Patent Application No.
PCT/EP2005/007747, filed Jul. 15, 2005, which in turn claims
priority from European Patent Application No. 04019695.8 and U.S.
Patent Application No. 60/603,069, both filed Aug. 19, 2004, all of
which are incorporated by reference in their entireties.
FIELD OF THE INVENTION
[0002] The invention relates to the use of PDE5 inhibitor, or of an
isomer thereof, or of a pharmaceutically acceptable salt thereof
for treating and/or preventing hypopigmentary disorders. In
particular, the invention relates to the use of Tadalafil and/or
Sildenafil, its isomers and pharmaceutically acceptable salts for
treating and/or preventing hypopigmentary disorders. The invention
also relates to methods of treatment and or prevention of
hypopigmentary disorders by administering PDE5 inhibitors.
BACKGROUND OF THE INVENTION
[0003] In the skin or hair, melanocytes are the sole source of the
pigment melanin. Melanin is synthesized within the melanocytes and
later transferred to the surrounding keratinocytes. The colour of
the skin is determined to a large extent by the amount and type of
melanin within the epidermis. In general dysfunction of the
melanocytes or the loss of the melanocytes itself leads to loss of
pigmentation. The mechanisms for the destruction of melanocytes are
likely to be multiple and complex, possibly a composite of several
normal processes influencing melanocyte function, proliferation
and/or survival. Also the pathomechanism of hyperpigmentary
disorders is largely unclear.
[0004] Vitiligo, for example is a pigmentation disorder afflicting
up to 2% of the worldwide population. It is a specific type of
leukoderma manifested characteristically by depigmentation of the
epidermis, best described as an acquired, progressive disorder that
selectively destroys some or all melanocytes. The vitiligo disease
is characterized by milky white macules on the skin, either due to
missing melanin pigment or to complete absence of melanocytes in
the dermo-epidermal junction of vitiligo areas. Vitiligo tends to
be progressive throughout the life of affected individuals. Other
disorders of hypopigmentation that are caused by a defect in
melanin production or transfer include the Chediak-Higashi
syndrome, Hermansky-Pudlak syndrome, the Waardenburg syndromes
I-IV, the Angelman and Prader-Willi syndrome. Albinism instead is
characterized by genetic defects that impede the synthesis of
melanin. Piebaldism is characterized by the absence of melanin at
birth due to a deficiency of melanocytes. During embryogenesis
melanocytes fail to complete their migration from the neural crest
to the epidermis. In vitiligo some melanocytes can be found in
epidermis of early lesions that are only partially depigmented. In
late lesions that were totally depigmented, there is complete
absence of melanocytes. Also, there is a lack of knowledge about
the pathophysiology and mechanisms underlying most pigmentary
disorders.
[0005] At the moment there are still several hypotheses to explain
the possible causes of vitiligo: [0006] 1) Autoimmune disease:
Specific autoantibodies to melanocyte cell surface antigens are
present in the circulation of most patients with vitiligo. These
antibodies are unusual in persons with nonpigmentary skin diseases.
Vitiligo antibodies are shown to have the functional capacity to
kill pigment cells in vitro and can do so by two different
mechanisms: complement-dependent cytotoxicity and
antibody-dependent cellular cytotoxicity. [0007] 2)
Self-destruction of melanocytes as a consequence of aberrant
melanin biosynthesis: The autocytotoxic hypothesis is based on the
observation that phenol and some of its derivatives are capable of
killing pigment cells. Tyrosine, the substrate of the tyrosinase is
itself a phenol derivative, is oxidized into melanin via a complex
series of oxidative reactions. Some intermediates are capable of
forming radicals. It is thought that melanin synthesis is confined
within the melanosome to prevent these melanin precursors from
diffusing into the cell where they might disrupt essential
metabolic pathways. [0008] 3) Overproduction of neurotransmitters
leading to death of melanocytes: Melanocytes are neural crest
derived cells. A dysfunction of nervous function might be involved
in the pathogenesis of vitiligo as shown by an altered balance of
neuropeptides in vitiliginous skin. Neuropeptides are able to
induce melanocyte dendricity and participate in the regulation of
cell substrate adhesion, cell motility and shape. Neuropeptides may
also regulate melanin synthesis or affect melanosomal transfer to
surrounding keratinocytes. [0009] 4) More recently, also viral
infections as well as oxidative stress and hormonal causes are
discussed to be involved in the disease formation. [0010] 5)
Although the pathogenesis of vitiligo is still not known, there is
a genetic predisposition, demonstrated by the fact, that 40% of
vitiligo patients have a positive family history for this disease.
[0011] 6) A combination of some or all of above theories
[0012] Currently, no satisfying treatments exist for pigmentary
disorders. For example, at present, there is no specific therapy
for Vitiligo available without side effects and no innovative
therapeutic programs are under development. No single therapy
predictably produces good results in all patients and the responses
are highly variable: systemic photochemotherapy (PUVA) gives
satisfactory results only in some early disease states, however,
treatment is time-consuming and has a high risk of developing
cancer after prolonged treatment. Other therapies comprise systemic
steroids, e.g. prednisone, hydrocortisone or triamcinolone, which
however are also not suitable for prolonged treatment. In some
cases, transplantation of skin has given positive results. In
extreme cases, where the depigmented area has become very large,
total chemical depigmentation of the skin is performed to achieve a
homogeneous coloring of the skin.
[0013] Similarly, no specific and satisfactory treatment exists for
Pityriasis alba, a common hypopigmented dermatitis that occurs
primarily in school-aged children. Usually this disorder is left
untreated as treatments with corticosteroids or retinoic acid or
PUVA treatment are not very efficient.
[0014] Some pigmentary disorders, like vitiligo, have only skin
manifestations limited to the pigmentation alterations. However,
these disorders nevertheless pose severe psychological problems to
the patients, as the sharp borders of depigmented areas are readily
apparent to other persons, especially when occurring in the face.
Vitiligo can be disfiguring and stigmatising, thereby causing
significant psychological problems due to reduced social
acceptance. Also, vitiligo usually persists for the whole life.
[0015] There is therefore a need for a specific treatment of
hypopigmentary disorders, preferably vitiligo.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Further aspects of the present invention will become evident
by the figures and the following examples which are given to merely
illustrate the invention, not to limit the same.
[0017] FIG. 1 shows the influence of Sildenafil on dendrite
formation in melanocytes in a melanocyte dendrite outgrowth
assay.
DETAILED DESCRIPTION OF THE INVENTION
[0018] Surprisingly it was found, that PDE5 inhibitors are suitable
for the treatment and prevention of hypopigmentary disorders,
especially vitiligo. Especially preferred are the PDE5 inhibitors
Sildenafil, Tadalafil and Vardenafil, in particular Tadalafil and
Sildenafil.
[0019] Phosphodiesterase 5 or PDE5 is one member of a superfamily
of cyclic nucleotide hydrolysing enzymes that specifically cleaves
cyclic guanosine monophosphate (cGMP) which is a second messenger.
PDE5 inhibitors have originally been proposed to be useful in the
treatment of hypertension and angina, however, the main focus is
now their use in the treatment of erectile dysfunction. Other
suggested activities of PDE5 inhibitors are reversal of gastric
emptying, lowering blood pressure and pulmonary hypertension (see
Rotella D. P., 2001, Drugs of the Future, 26: 153-162). It has
never been proposed that the compounds of the invention are useful
in the treatment and/or prevention of hypopigmentary disorders.
[0020] A range of PDE5 inhibitors with proven or suggested
potential for use as medicine are known up to know. Such PDE5
inhibitors, which can be used according to the invention and which
are included by reference are:
Dihydrotriazolohydropurinone derivatives which are disclosed in WO
01/07441; purinone derivatives which are described in WO 94/00453;
Pyrazolo[3,4-d]pyrimidinine-4-one derivatives which are described
in EP 0636626; WO 96/28429; WO 96/28448; WO 94/28902; U.S. Pat. No.
5,294,612 and EP 0995751;
1,6-Dihydro-7H-pyrazolo-[3,4-d]pyrimidin-4-one derivatives which
are described in EP 0201188; WO 88/00192; EP 0995750; EP 1057829;
EP 1092720; WO 01/127101; WO 01/27112; WO 01/27113 and WO 00/27848;
Imidazotriazinone derivatives which are described in WO 99/24433,
WO 99/67244; and EP 1092719; Imidazoquinazolinone derivatives which
are described in WO 99/64004; Pyrazolopyridopyrimidine derivatives
which are described in Krupinski et al., 2001, Bioorg. Med. Chem.
Lett., 11: 2461-2464 Pyrrolopyrimidinone derivatives which are
disclosed in WO 01/60825; Quinazolinone and Pyridopyrimidone
derivatives which are disclosed in WO 93/12095 and WO 94/05661 and
JP 8104679; JP 07330777 and JP 07267961; Fused pyrimidine
derivatives which are disclosed in Lee et al., 1995, J. Med. Chem.,
38: 3547-3557, WO 98/06722, WO 02/26745; DE 19752952; WO 99/55708;
DE 19943815; DE 19944604; Jonas et al., 2002, Chem. Abstr. 136:
85819; WO 99/43674; WO 00/59912; WO 98/17668; WO 02/18389; U.S.
Pat. No. 5,436,233; EP 728759; U.S. Pat. No. 5,525,604; WO
93/07124; WO 96/26940; WO 95/06648; WO 98/08848; WO 99/43679; WO
99/43674; DE 19942474; WO 01/12608; WO 00/15222 and WO 02/20489;
Pyrimidine derivatives which are described in WO 01/19802; WO
01/83460; WO 98/23597; EP 0640599, WO 96/05176, WO 98/07430, WO
99/42452, WO 01/05770 and WO 00/56719; Isoquinoline derivatives
which are disclosed in WO 98/38168, WO 00/12503; EP 128462 and JP
12281654; Hexahydropyrazino-pyrido-indole-1,4-dione derivatives
which are disclosed in WO 95/19978, WO 97/03675, U.S. Pat. No.
6,143,746, WO 96/32003, WO 95/19978, WO 97/03985, WO 01/80860, WO
01/808686, WO 00/66114, WO 02/10166, WO 02/28858, WO 97/43287, U.S.
Pat. No. 6,306,870, U.S. Pat. No. 6,043,252 and WO 01/87038;
Anthranilic acid diamide derivatives which are disclosed in WO
95/18097 and WO 99/54284, Pyridocarbazolone derivatives which are
described in WO 98/53819, WO 99/26946, WO 00/32195 and WO 99/28319;
Indole and Benzimidazole derivatives which are disclosed in WO
96/32379, WO 99/51574, WO 98/15530, WO 97/24334, WO 99/00373, WO
00/39099, WO 99/00373, WO 00/34277, JP 101824549, WO 97/03070, WO
99/00350, WO 00/39099, WO 00/39097, WO 99/0372 and WO 99/21831;
Pyrazoloquinoline and pyrazolopyridine derivatives which are
disclosed in U.S. Pat. No. 5,488,055 and WO 96/28159;
Imidazopyridopyrazinones which are disclosed in WO 00/43392 and DE
19510965; Quinazolinedione phtalimide derivatives which are
disclosed in WO 01/44228 and WO 00/20412; Cyclobutendione
derivatives which are disclosed in WO 00/51973, WO 00/63170, WO
00/63160 and WO 94/29277; Dual PDE1/5 inhibitors which are
disclosed in WO 91/19717 and WO 97/19947 (see Haning et al.,
Progress in Medicinal Chemistry, 2003, 41: 249-306 for a review on
PDE 5 inhibitors).
[0021] PDE5 inhibitors for the use according to the present
invention include: the pyrazolo[4,3-d]pyrimidin-7-ones disclosed in
EP-A-0463756, especially Sildenafil and salts and hydrates thereof;
the pyrazolo[4,3-d]pyrimidin-7-ones disclosed in EP-A-0526004; the
pyrazolo[4,3-d]pyrimidin-7-ones disclosed in published
international patent application WO 93/06104; the isomeric
pyrazolo[3,4-d]pyrimidin-4-ones disclosed in published
international patent application WO 93/07149; the quinazolin-4-ones
disclosed in published international patent application WO
93/12095; the pyrido[3,2-d]pyrimidin-4-ones disclosed in published
international patent application WO 94/05661; the purin-6-ones
disclosed in published international patent application WO
94/00453; the pyrazolo[4,3-d]pyrimidin-7-ones disclosed in
published international patent application WO 98/49166; the
pyrazolo[4,3-d]pyrimidin-7-ones disclosed in published
international patent application WO 99/54333; the
pyrazolo[4,3-d]pyrimidin-4-ones disclosed in EP-A-0995751; the
pyrazolo[4,3-d]pyrimidin-7-ones disclosed in published
international patent application WO 00/24745; the compounds
disclosed in published international application WO95/19978; the
compounds disclosed in published international application WO
99/24433 and the compounds disclosed in published international
application WO 93/07124.
[0022] It is to be understood that the contents of the above
published patent applications, and in particular the general
formulae and exemplified compounds therein are incorporated herein
in their entirety by reference thereto.
[0023] PDE5 inhibitors which may be used according to the invention
include
3-ethyl[2-(4-morpholinylmethyl)benzylamino]-2,3-dihydro-1H-imidaz-
o[4,5-g]quinazoline-2-thione;
1-(2-chlorobenzyl)-3-isobutyryl-2-propylindole carboxamide;
9-bromo-2-(3-hydroxypropoxy)-5-(3-pyridylmethyl)-4H-pyrido[3,2,1-jk]-carb-
azol-4-one;
4-(1,3-benzodioxol-5-ylmethylamino)-2-(1-imidazolyl)-6-methylthieno[2,3-d-
]pyrimidine;
6-(2-isopropyl-4,5,6,7-tetrahydropyrazolo[1,5-a]pyridine-3-yl)-5-methyl)--
5-methyl-2,3,4,5-tetrahydropyridazin-3-one;
5-(4-methylbenzyl)-3-(1-methyl-4-phenylbutyl)-3,6-dihydro[1,2,3]triazolo[-
4,5-d]pyrimidin-7-one;
3-(1-methyl-4-phenylbutyl)-5-pyridin-4-ylmethyl-3,6-dihydro[1,2,3]triazol-
o[4,5-d]pyrimidin-7-one;
5-(4-bromobenzyl)-3-(1-methyl-4-phenylbutyl)-3,6-dihydro[1,2,3]-triazolo[-
4,5-d]pyrimidin-7-one;
5-benzyl-3-(1-methyl-4-phenylbutyl)-3,6-dihydro-[1,2,3]-triazolo[4,5d]pyr-
imidin-7-one; 5-(3,4-dimethoxybenzyl) (I-methyl
phenylbutyl)-3,6-dihydro-[1,2,3]-triazolo-[4,5d]pyrimidin-7-one;
5-(3,4-dichlorobenzyl)-3-(1-methyl-4-phenylbutyl)-3,6-dihydro-[1,2,3]-tri-
azolo[4,5d]pyrimidin-7-one;
5-biphenyl-4-ylmethyl-3-(1-methyl-4-phenylbutyl)-3,6-dihydro-[1,2,3]-tria-
zolo[4,5d]pyrimidin-7-one;
5-(4-aminobenzyl)-3-(1-methyl-4-phenylbutyl)-3,6-dihydro-[1,2,3]-triazolo-
[4,5-d]pyrimidin-7-one;
5-(hydroxyphenylmethyl)-3-(1-methyl-4-phenylbutyl)-3,6-dihydro-[1,2,3]-tr-
iazolo-[4,5d]pyrimidin-7-one;
5-benzo[1,3]-dioxol-5-ylmethyl-3-[1-methyl-4-phenylbutyl]-3,6-dihydro[1,2-
,3]-triazolo[4,5-d]pyrimidin-7-one;
N-4-[3-(1-methyl-4-phenylbutyl)-7-oxo-6,7-dihydro-3H-[1,2,3]-triazolo-[4,-
5-d]pyrimidin-5-ylmethyl]phenylacetamide;
5-benzoyl-3-(1-methyl-4-phenylbutyl)-3,6-dihydro-[1,2,3]triazolo[4,5-d]-p-
yrimidin-7-one;
3-(1-methyl-4-phenylbutyl)-5-[4-(morpholine-4-sulphinyl)benzyl]-3,6-dihyd-
ro[1,2,3]triazolo[4,5-d]pyrimidin-7-one;
3-(1-methyl-4-phenylbutyl)-5-[3-(morpholine-4-sulphonyl)benzyl]-3,6-dihyd-
ro[1,2,3]triazolo[4,5-d]pyrimidin-7-one;
N-methyl-4-[3-(1-methyl-4-phenylbutyl)-7-oxo-6,7-dihydro-3H-[1,2,3]-triaz-
olo-[4,5-d]pyrimidin-5-ylmethyl]-benzenesulphonamide;
N-(2-dimethylaminoethyl)-4-[3-(1-methyl-4-phenylbutyl)-7-oxo-6,7-dihydro--
3H-[1,2,3]triazolo[4,5-d]pyrimidin-5-ylmethyl]benzenesulphonamide;
N-(2-hydroxyethyl)-4-[3-(1-methyl-4-phenylbutyl)-7-oxo-6,7-dihydro-3H-[1,-
2,3]triazolo[4,5-d]pyrimidin-5-ylmethyl]benzenesulphonamide; ethyl
1-[3-[3-(1-methyl-4-phenylbutyl)-7-oxo-6,7-dihydro-3H-[1,2,3]-triazolo-[4-
,5-d]pyrimidin-5-ylmethyl]benzenesulphonyl]piperidinecarboxylate;
3-(1-methyl-4-phenylbutyl)-5-[4-(4-methylpiperazin-1-sulphonyl)benzyl]-3,-
6-dihydro-[1,2,3]triazolo[4,5-d]pyrimidin-7-one;
5-benzo[1,3]dioxol-5-ylmethyl-3-[1-ethyl-heptyl]-3,6-dihydro-[1,2,3]-tria-
zolo[4,5-d]pyrimidin-7-one;
3-[1-(1-hydroxyethyl)-4-phenylbutyl]-5-[4-(morpholine-4-sulphonyl)benzyl]-
-3,6-dihydro-[1,2,3]triazolo[4,5-d]pyrimidin-7-one;
5-[6-fluoro-1-(phenylmethyl)-1H-indazol-3-yl]-2-furanmethanol;
1-benzyl-6-fluoro-3-[5-(hydroxymethyl)furan-2-yl]-1H-indazole;
2-(1H-imidazol-1-yl)-6-methoxy-4-(2-methoxyethylamino)quinazoline;
1-[[3-(7,8-dihydro-8-oxo-1H-imidazo[4,5-g]quinazolin-6-yl)-4-propoxypheny-
l]sulphonyl]-4-methylpiperazine;
4-(3-chloro-4-methoxybenzylamino)-1-(4-hydroxypiperidin-1-yl)phthalazine--
6-carbonitrile;
1-[6-chloro-4-(3,4-methylendioxybenzylamino)quinazolin-2-yl]piperidin-4-c-
arboxylic acid; (6R,12aR)-6-(1,3-benzodioxol-5-yl)-2-methyl-1
2,3,4,6,7,12,12a-octa-hydropyrazino[2',1':6,1]pyrido[3,4-b]indole-1,4-dio-
ne (Tadalafil);
(6R,12aR)-2,3,6,7,12,12a-hexahydro-2-methyl-6-(3,4-methylenedioxyphenyl)--
pyrazino[2',1':6,1]pyrido[3,4-b]indole-1,4-dione;
4-ethoxy-2-phenylcycloheptylimidazole;
(6-bromo-3-methoxymethylimidazo[1,2-a]pyrazin-8-yl)methylamine;
8-[(phenylmethyl)thio]-4-(1-morpholinyl)-2-(1-piperazinyl)pyrimidino[4,5--
d]pyrimidine;
(+)-cis-5-methyl-2-[4-(trifluoromethyl)benzyl]-3,4,5,6a,7,8,9-octahydrocy-
clopent[4,5]imidazo[2,1-b]purin-4-one;
cis-2-hexyl-5-methyl-3,4,5,6a,7,8,9,9a-octahydrocyclopent[4,5]imidazo[2,1-
-b]purin-4-one;
5-[2-ethoxy-5-(4-methyl-1-piperazinylsulphonyl)phenyl]-1-methyl-3-n-propy-
l-1,6-dihydro-7H-pyrazolo[4,3-d]pyrimidin-7-one (Sildenafil);
1-[[3(6,7-dihydro-1-methyl-7-oxo-3-propyl-1H-pyrazolo[4,3-d]pyrimidin-5-y-
l)-4-ethoxyphenyl]sulfonyl]-4-methylpiperazine;
2-(2-propoxyphenyl)purin-6(1H)-one;
2-(2-propoxyphenyl)-1,7-dihydro-5H-purin-6-one; methyl
2-(2-methylpyridin-4-ylmethyl)-1-oxo-8-(2-pyrimidinylmethoxy)-4-(3,4,5-tr-
imethoxyphenyl)-1,2-dihydro-[2,7]naphthyridin-3-carboxylate; methyl
2-(4-aminophenyl)-1-oxo-7-(2-pyridinylmethoxy)-4-(3,4,5-trimethoxyphenyl)-
-1,2-dihydroisoquinoline-3-carboxylate;
2-[2-ethoxy-5-(4-ethylpiperazin-1-ylsulfonyl)phenyl]-5-methyl-7-propylimi-
dazo[5,1-f][1,2,4]triazin-4(3H)-one (Vardenafil);
3,4-dihydro-6-[4-(3,4-dimethoxybenzoyl)-1-piperazinyl]-2-(1H)-quinolinone
(vesnarinone);
1-cyclopentyl-3-methyl-6-(4-pyridyl)pyrazolo[3,4-d]pyrimidin-4(5H)-one;
1-cyclopentyl-6-(3-ethoxy-4-pyridin-8-azapurin-6-one;
3,6-dihydro-5-(o-propoxyphenyl)-7H-[1,2,3]triazolo[4,5-d]pyrimidin-7-one
and 4-methyl-5-(4-pyridinyl)thiazole-2-carboxamide and the
pharmacologically acceptable salts of these compounds.
[0024] Other PDE5 inhibitors useful in conjunction with the present
invention include: [0025]
4-bromo-5-(pyridylmethylamino)-6-[3-(4-chlorophenyl)-propoxy]-3(2H)pyrida-
zinone; [0026]
1-[4-[(1,3-benzodioxol-5-ylmethyl)amino]-6-chloro-2-quinozolinyl]-4-piper-
idine-carboxylic acid, monosodium salt; [0027]
(+)-cis-5,6a,7,9,9,9a-hexahydro-2-[4-(trifluoromethyl)-phenylmethyl-5-met-
hyl-cyclopent-4,5]imidazo[2,1-b]purin-4(3H)one; [0028]
furazlocillin; [0029]
cis-2-hexyl-5-methyl-3,4,5,6a,7,8,9,9a-octahydrocyclopent[4,5]-imi-
dazo[2,1-b]purin-4-one; [0030]
3-acetyl-1-(2-chlorobenzyl)-2-propylindole-6-carboxylate;
3-acetyl-1-(2-chlorobenzyl)-2-propylindole-6-carboxylate; [0031]
4-bromo-5-(3-pyridylmethylamino)-6-(3-(4-chlorophenyl)propoxy)-3-(2H)pyri-
dazinone; [0032]
1-methyl-5(5-morpholinoacetyl-2-n-propoxyphenyl)-3-n-propyl-1,6-dihydro-7-
H-pyrazolo[4,3-d]pyrimidin-7-one; [0033]
1-[4-[(1,3-benzodioxol-5-ylmethyl)amino]-6-chloro-2-quinazolinyl]-4-piper-
idinecarboxylic acid, monosodium salt; [0034] Pharmaprojects No.
4516 (Glaxo Wellcome); Pharmaprojects No. 5051 (Bayer); [0035]
Pharmaprojects No. 5064 (Kyowa Hakko; see WO 96/26940); [0036]
Pharmaprojects No. 5069 (Schering Plough); GF-196960 (Glaxo
Wellcome); Bay-38-3045 & 38-9456 (Bayer); [0037]
(S)-2-(2-Hydroxymethyl-1-pyrrolidinyl)-4-(3-chloro-4-methoxybenzylamino)--
5-[(2-pyrimidinylmethyl)carbamoyl]pyrimidine; [0038] DA-8159
(Benzenesulfonamide,
3-(4,7-dihydro-1-methyl-7-oxo-3-propyl-1H-pyrazolo[4,3-d]pyrimidin-5-yl)--
N-[2-(1-methyl-2-pyrrolidinyl)ethyl]-4-propoxy-); [0039]
EMD-221829; [0040] UK 357903 (piperazine,
1-ethyl-4-[[5-[3-ethyl-4,7-dihydro-7-oxo-2-(2-pyridinylmethyl)-2H-pyrazol-
o[4,3-d]pyrimidin-5-yl]-6-(2-methoxyethoxy)-3-pyridinyl]sulfonyl]-);
[0041] UK 114542.
[0042] Preferred PDE5 inhibitors include:
BMS-341400 which has the following structure:
##STR00001##
BMS-281384 which has the following structure:
##STR00002##
BMS-263504, LAS-34179, LAS-30902, LAS-34837, AWD-12-250,
[0043] OSI-461 (CAS RN No. 227619-96-7) which has the following
structure:
##STR00003##
Exisulind which has the following structure:
##STR00004##
Sophoflavescenol which has the following structure:
##STR00005##
DA-8159 (Benzenesulfonamide,
3-(4,7-dihydro-1-methyl-7-oxo-3-propyl-1H-pyrazolo[4,3-d]pyrimidin-5-yl)--
N-[2-(1-methyl-2-pyrrolidinyl)ethyl]-4-propoxy-); E-8010
(6-Phthalazinecarbonitrile,
4-[[(3-chloro-4-methoxyphenyl)methyl]amino]-1-(4-hydroxy-1-piperidinyl)-
and its monohydrochloride salt); E4010
([4-(3-chloro-4-methoxybenzyl)amino-1-(4-hydroxy)piperidino]-6-phthalazin-
e carbonitrile monohydrochloride); FR-181074; FR-226807 (Benzamide,
N-[(3,4-dimethoxyphenyl)methyl]-2-[[(1R)-2-hydroxy-1-methylethyl]amino]-5-
-nitro-); FR-189318; FR-229934, which has the following
structure:
##STR00006##
DMPPO, GF-248
(1-Methyl-5-(5-morpholinoacetyl-2-propoxyphenyl)-3-propyl-1,6-dihydro-7H--
pyrazolo[4,3-d]pyrimidin-7-one), KF-31327
(3-Ethyl-8-[2-(4-hydroxymethylpiperidino)
benzylamino]-2,3-dihydro-1H-imidazo[4,5-g]quinazoline-2-thione
dihydrochloride); EMD-82639; EMR-62203; NCX-911 (Sildenafil
nitrate); NM-702 which has the following structure:
##STR00007##
QAD-171A which has the following structure:
##STR00008##
OPC-35564 which has the following structure:
##STR00009##
UK-114542; UK-357903; UK-369003;
[0044] UK-83405 which has the following structure:
##STR00010##
UK-114502; SR-265579 (4H-Pyrazolo[3,4-d]pyrimidin-4-one,
1-cyclopentyl-6-(3-ethoxy-4-pyridinyl)-3-ethyl-1,3a-dihydro-);
SCH-446132 which has the following structure:
##STR00011##
and which is disclosed in WO 00/224698; Sch-51866
(Cyclopent[4,5]imidazo[2,1-b]purin-4(1H)-one,5,6a,7,8,9,9a-hexahydro-5-me-
thyl-2-[[4-(trifluoromethyl)phenyl]methyl]-, (6aR,9aS)-rel-) which
has the following structure:
##STR00012##
Sch-59498; SK-3530, SB-96231
(2-(2-Propoxyphenyl)-1,7-dihydro-6-purinone; SKF-96231); WIN-65579
(4H-Pyrazolo[3,4-d]pyrimidin-4-one,
1-cyclopentyl-6-(3-ethoxy-4-pyridinyl)-3-ethyl-1,7-dihydro-);
Avanafil (5-Pyrimidinecarboxamide,
4-[[(3-chloro-4-methoxyphenyl)methyl]amino]-2-[(2S)-2-(hydroxymethyl)-1-p-
yrrolidinyl]-N-(2-pyrimidinylmethyl)-); T-0156 which has the
following structure:
##STR00013##
T-1032 (3-Isoquinolinecarboxylic acid,
2-(4-aminophenyl)-1,2-dihydro-1-oxo-7-(2-pyridinylmethoxy)-4-(3,4,5-trime-
thoxyphenyl)-, methyl ester, sulfate); YC-1 (2-Furanmethanol,
5-[1-(phenylmethyl)-1H-indazol-3-yl]-) and salts and esters
thereof, or, where the compound is already a salt, a different salt
thereof.
[0045] Further preferred PDE5 inhibitors for the use according to
the present invention include: [0046]
5-[2-ethoxy-5-(4-methyl-1-piperazinylsulphonyl)phenyl]-1-methyl-3-n-propy-
l-1,6-dihydro-7H-pyrazolo[4,3-d]pyrimidin-7-one (Sildenafil) also
known as
1-[[3-(4,7-dihydro-1-methyl-7-oxo-3-propyl-1H-pyrazolo[4,3-d]pyrimidin-5--
yl)-4-ethoxyphenyl]sulphonyl]-4-methylpiperazine ((see
EP-A-0463756); see Example 1 of the present invention) [0047]
5-(2-ethoxy-5-morpholinoacetylphenyl)-1-methyl-3-n-propyl-1,6-dihydro-7H--
pyrazolo[4,3-d]pyrimidin-7-one (see EP-A-0526004); [0048]
3-ethyl-5-[5-(4-ethylpiperazin-1-ylsulphonyl)-2-n-propoxyphenyl]-2-(pyrid-
in-2-yl)methyl-2,6-dihydro-7H-pyrazolo[4,3-d]pyrimidin-7-one (see
WO98/49166); [0049]
3-ethyl-5-[5-(4-ethylpiperazin-1-ylsulphonyl)-2-(2-methoxyethoxy)pyridin--
3-yl]-2-(pyridin-2-yl)methyl-2,6-dihydro-7H-pyrazolo[4,3-d]pyrimidin-7-one
(see WO99/54333); [0050]
(+)-3-ethyl-5-[5-(4-ethylpiperazin-1-ylsulphonyl)-2-(2-methoxy-1(R)-methy-
lethoxy)pyridin-3-yl]-2-methyl-2,6-dihydro-7H-pyrazolo[4,3-d]pyrimidin-7-o-
ne, also known as
3-ethyl-5-{5-[4-ethylpiperazin-1-ylsulphonyl]-2-([(1R)-2-methoxy-1-methyl-
ethyl]oxy)pyridin-3-yl}-2-methyl-2,6-dihydro-7H-pyrazolo[4,3-d]pyrimidin-7-
-one (see WO99/54333); [0051]
5-[2-ethoxy-5-(4-ethylpiperazin-1-ylsulphonyl)pyridin-3-yl]-3-ethyl-2-[2--
methoxyethyl]-2,6-dihydro-7H-pyrazolo[4,3-d]pyrimidin-7-one, also
known as
1-{6-ethoxy-5-[3-ethyl-6,7-dihydro-2-(2-methoxyethyl)-7-oxo-2H-pyrazolo[4-
,3-d]pyrimidin-5-yl]-3-pyridylsulphonyl}-4-ethylpiperazine; [0052]
5-[2-iso-Butoxy-5-(4-ethylpiperazin-1-ylsulphonyl)pyridin-3-yl]-3-ethyl-2-
-(1-methylpiperidin-4-yl)-2,6-dihydro-7H-pyrazolo[4,3-d]pyrimidin-7-one;
[0053]
5-[2-Ethoxy-5-(4-ethylpiperazin-1-ylsulphonyl)pyridin-3-yl]-3-ethy-
l-2-phenyl-2,6-dihydro-7H-pyrazolo[4,3-d]pyrimidin-7-one; [0054]
5-(5-Acetyl-2-propoxy-3-pyridinyl)-3-ethyl-2-(1-isopropyl-3-azetidinyl)-2-
,6-dihydro-7H-pyrazolo[4,3-d]pyrimidin-7-one; [0055]
5-(5-Acetyl-2-butoxy-3-pyridinyl)-3-ethyl-2-(1-ethyl-3-azetidinyl)-2,6-di-
hydro-7H-pyrazolo[4,3-d]pyrimidin-7-one; [0056]
(6R,12aR)-2,3,6,7,12,12a-hexahydro-2-methyl-6-(3,4-methylenedioxyphenyl)--
pyrazino[2',1':6,1]pyrido[3,4-b]indole-1,4-dione (Tadalafil;
IC-351; see Example 2 of the present application), i.e. the
compound of examples 78 and 95 of published international
application WO95/19978, as well as the compound of examples 1, 3, 7
and 8 of WO95/19978; [0057]
2-[2-ethoxy-5-(4-ethyl-piperazin-1-yl-1-sulphonyl)-phenyl]-5-methyl-7-pro-
pyl-3H-imidazo[5,1-f][1,2,4]triazin-4-one (Vardenafil) also known
as
1-[[3-(3,4-dihydro-5-methyl-4-oxo-7-propylimidazo[5,1-f][1,2,4]triazin-2--
yl)-4-ethoxyphenyl]sulphonyl]-4-ethylpiperazine, i.e. the compound
of examples 20, 19, 337 and 336 of published international
application WO99/24433; and [0058] the compound of example 11 of
published international application WO93/07124 (EISAI); and [0059]
compounds 3 and 14 from Rotella D P, J. Med. Chem., 2000, 43,
1257.
[0060] A particularly preferred PDE5 inhibitor of the present
invention is Sildenafil, which has the following structure:
##STR00014##
or a pharmaceutically acceptable salt thereof, in particular the
citrate salt.
[0061] Alternative names for Sildenafil are
5-[2-Ethoxy-5-(4-methyl-1-piperazinylsulfonyl)phenyl]-1-methyl-3-n-propyl-
-1,6-dihydro-7H-pyrazolo[4,3-d]pyrimidin-7-one and
1-[[3-(4,7-dihydro-1-methyl-7-oxo-3-propyl-1H-pyrazolo[4,3-d]pyrimidin-5--
yl)-4-ethoxyphenyl]sulfonyl]-4-methyl-piperazine. The synthesis of
the compound is well known for a skilled person and for example
described in described in EP 0 463 756B1. The CAS No. is
139755-83-2.
The preferred salt of Sildenafil useable according to the invention
is Sildenafil citrate. Another particularly preferred PDE5
inhibitor of the present invention is Tadalafil, which has the
following structure:
##STR00015##
[0062] Alternative names for Tadalafil are
Pyrazino[1',2':1,6]pyrido[3,4-b]indole-1,4-dione,
6-(1,3-benzodioxol-5-yl)-2,3,6,7,12,12a-hexahydro-2-methyl-,
(6R,12aR)- and Pyrazino[1',2':1,6]pyrido[3,4-b]indole-1,4-dione,
6-(1,3-benzodioxol-5-yl)-2,3,6,7,12,12a-hexahydro-2-methyl-,
(6R-trans)- and
(6R,12aR)-2,3,6,7,12,12a-hexahydro-2-methyl-6-(3,4-methylenedioxyphen-
yl)pyrazino[1',2':1,6]pyrido[3,4-b]indole-1,4-dione and Cialis; GF
196960; IC 351 and ICOS 351. The synthesis of the compound is well
known for a skilled person and for example described in described
in WO 95/19978. The CAS Reg. No is 171596-29-5.
[0063] The suitability of any particular PDE5 inhibitor can be
readily determined by evaluation of its potency and selectivity
using literature methods followed by evaluation of its toxicity,
absorption, metabolism, pharmacokinetics, etc in accordance with
standard pharmaceutical practice.
[0064] Preferably, the PDE5 inhibitors have an IC.sub.50 at less
than 100 nanomolar, more preferably, at less than 50 nanomolar,
more preferably still at less than 10 nanomolar.
[0065] IC.sub.50 values for the PDE5 inhibitors may be determined
using established literature methodology, for example as described
in EP0463756 and EP0526004.
[0066] Preferably the PDE5 inhibitors used in the invention are
selective for the PDE5 enzyme. Preferably they are selective over
PDE3, more preferably over PDE3 and PDE4. Preferably, the PDE5
inhibitors of the invention have a selectivity ratio greater than
100, more preferably greater than 300, over PDE3 and more
preferably over PDE3 and PDE4. The term "to have a selectivity
ratio for enzyme z greater than x . . . over enzyme y", as used
herein, is meant to designate that a compound/substance
characterised by such term have an x-times greater preference for
enzyme z than for enzyme y.
[0067] Selectivity ratios may readily be determined by the skilled
person. IC.sub.50 values for the PDE3 and PDE4 enzyme may be
determined using established literature methodology, see S. A.
Ballard et al, Journal of Urology, 1998, vol. 159, pages
2164-2171.
[0068] Surprisingly, the PDE5 inhibitors, such as Sildenafil and
Tadalafil, can be used to treat hypopigmentary disorders,
especially vitiligo. The present invention therefore relates to the
use of a PDE5 inhibitor for the manufacture of a medicament for
treating and/or preventing hypopigmentary disorders, especially
vitiligo. Furthermore the present invention relates to a method of
treating and/or preventing hypopigmentary disorders, especially
vitiligo comprising administering to a mammal a PDE5 inhibitor.
[0069] Surprisingly it was found that compounds according to
formula (I):
##STR00016##
or isomers thereof or pharmaceutically acceptable salts thereof,
are useful in the treatment and prevention of hypopigmentary
disorders, especially vitiligo.
[0070] Moreover it was surprisingly found that a PDE5 inhibitor,
especially Sildenafil, is especially suitable for the treatment and
prevention of hypopigmentary diseases which have an inflammatory
and/or autoimmune component and/or in which T cell activation and
proliferation plays a role, especially preferred vitiligo. Such
inflammatory and/or autoimmune component may form part of the
hypopigmentary disease or may be in addition thereto.
[0071] The present invention therefore relates to the use of a
compound according to formula
##STR00017##
or an isomer thereof, or a pharmaceutically acceptable salt
thereof, for the manufacture of a medicament for treating and/or
preventing hypopigmentary disorders, especially vitiligo.
[0072] In a preferred embodiment, the compound is Sildenafil or a
pharmaceutically acceptable salt thereof, in particular the citrate
salt.
[0073] Surprisingly it was found that compounds according to
formula (II)
##STR00018##
or isomers thereof or pharmaceutically acceptable salts thereof,
are useful in the treatment and prevention of hypopigmentary
disorders, especially vitiligo.
[0074] Moreover it was surprisingly found that a PDE5 inhibitor,
especially Tadalafil is especially suitable for the treatment and
prevention of hypopigmentary diseases which have an inflammatory
and/or autoimmune component and/or in which T cell activation and
proliferation plays a role, especially preferred vitiligo. Such
inflammatory and/or autoimmune component may form part of the
hypopigmentary disease or may be in addition thereto.
[0075] The present invention therefore relates to the use of a
compound according to formula (II):
##STR00019##
or an isomer thereof, or a pharmaceutically acceptable salt
thereof, for the manufacture of a medicament for treating and/or
preventing hypopigmentary disorders, especially vitiligo. In a
preferred embodiment, the compound is Tadalafil or a
pharmaceutically acceptable salt thereof.
[0076] The invention also relates to a method of treating and/or
preventing hypopigmentary disorders, especially vitiligo,
comprising administering to a mammal a compound according to
formula (I):
##STR00020##
or an isomer thereof, or a pharmaceutically acceptable salt
thereof, in particular the citrate salt.
[0077] In an even more preferred embodiment, the compound is
selected from Sildenafil or a pharmaceutically acceptable salt
thereof, in particular the citrate salt.
[0078] The invention also relates to a method of treating and/or
preventing hypopigmentary disorders, especially vitiligo,
comprising administering to a mammal a compound according to
formula (II):
##STR00021##
or an isomer thereof or a pharmaceutically acceptable salt
thereof.
[0079] In an even more preferred embodiment, the compound is
selected from Tadalafil or a pharmaceutically acceptable salt
thereof.
[0080] In one embodiment, the hypopigmentary disorder has an
inflammatory and/or an autoimmune component. Preferably the
hypopigmentary disorder is selected from albinism, vitiligo,
postinflammatory hypopigmentation, piebaldism, Pityariasis alba,
Hypomelanoses, Leukodermas, hypopigmentation occurring e.g. after
externally induced peels, e.g. chemical peels, e.g. with phenol, or
laser or cryo-surgery of the skin, Chediak-Higashi syndrome,
Hermansky-Pudlak syndrome, the Angelman and Prader-Willi syndrome,
wherein, more preferably, the hypopigmentary disorder is a disorder
in which T cell activation and proliferation plays a role, and
which hypopigmentary disorder is more preferably selected from
post-inflammatory hypopigmentation and vitiligo. In the most
preferred embodiment, the hypopigmentary disorder is vitiligo.
[0081] Methods of production of the compounds according to the
present invention are well known to someone skilled in the art, and
are described e.g. in, the contents of the documents cited above
which are hereby incorporated by reference.
[0082] Preferably, the medicament according to the present
invention is prepared in a form suitable for topical use,
preferably in form of an ointment, a gel, a plaster, an emulsion, a
lotion, a foam, a cream, a cream of a mixed phase or amphiphilic
emulsion system (oil/water-water/oil mixed phase), a liposome, a
transfersome, a paste or a powder, or a solution or suspension.
[0083] In one embodiment, the compound is applied topically or
systemically or via a combination of the two routes, preferably
topically.
[0084] The objects of the present invention are also solved by a
composition comprising a PDE5 inhibitor useable according to the
invention and one or more further active ingredients suitable for
the treatment and/or prevention of hypopigmentary disorders.
Preferably, such composition is used as a pharmaceutical.
[0085] In a preferred embodiment the objects of the present
invention are solved by a composition comprising a compound
according to formula (I)
##STR00022##
or an isomer thereof, or a pharmaceutically acceptable salt
thereof, and one or more further active ingredients suitable for
the treatment and/or prevention of hypopigmentary disorders.
[0086] In a preferred embodiment the objects of the present
invention are also solved by a composition comprising a compound
according to formula (II)
##STR00023##
or an isomer thereof, or a pharmaceutically acceptable salt
thereof, and one or more further active ingredients suitable for
the treatment and/or prevention of hypopigmentary disorders.
Preferably, such composition is used as a pharmaceutical.
[0087] In one embodiment, the further active ingredient is selected
from the group consisting of cyclosporin A, cyclosporin G,
cyclosporin B, cyclosporin C, cyclosporin D, dihydro-cyclosporin D,
cyclosporin E, cyclosporin F, cyclosporin H, cyclosporin I,
ASM-240, pimecrolimus, tacrolimus, 13-desmethyl-derivatives of
tacrolimus (L-685487), L-683519 and/or 17-ethyl-derivatives of
tacrolimus, preferably pimecrolimus, tacrolimus, or cyclosporin A,
most preferably tacrolimus; steroids, in particular betamethasone,
betamethasone-17-valerate, fluocinolone, triamcinolone,
triamcinolone acetonide, clobetasol, clobetasol propionate,
halobetasol, hydrocortisone, cortisone, desonide, prednisolone,
paramethasone, methylprednisolone, dexamethasone, deflazacort;
vitamin D analogues, in particular calcipotriol; pseudocatalase;
levamisole, fluorouracil; alpha-MSH; clofazimine; thiambutosine BP;
chloroquine; penicillamine; tar; minoxidil; inosiplex;
mechlorethamine; cyclophosphamide; anapsos; antioxidants like
Gingko biloba, canthaxanthine, beta-carotene, alpha-tocopherol, a
combination of alpha-tocopherol ubiquinone seleno-methionine and
methionine; pentoxifylline; vitamins and trace elements, in
particular vitamin B12, folic acid, vitamin C, vitamin E, copper
salts, human placental extract, khellin and phenylalanine.
[0088] Preferably, the composition according to the present
invention is formulated for topical use, more preferably in form of
an ointment, a gel, a plaster, an emulsion, a lotion, a foam, a
cream, a cream of a mixed phase or amphiphilic emulsion system
(oil/water-water/oil mixed phase), a liposome, a transfersome, a
paste or a powder, or a solution or suspension.
[0089] The objects of the present invention are furthermore solved
by the use of the composition according to the present invention
for the manufacture of a medicament for the treatment and/or
prevention of hypopigmentary disorders.
Hypopigmentary Disorders
[0090] Hypopigmentary disorders according to the present invention
are non-malignant disorders of the skin in mammals, including
humans which are characterized by a decrease in pigmentation of the
skin compared to healthy individuals. Such decrease in pigmentation
may occur locally, as e.g. in mild forms of vitiligo, or may affect
the whole skin. Such decrease in pigmentation may result in total
loss of pigmentation, as e.g. in affected skin areas of vitiligo
patients, or may result in "lighter" but still pigmented skin as in
Pityriasis alba. In some embodiments, the hypopigmentary disorders,
according to the present invention, have an inflammatory and/or an
autoimmune component. As used herein, the term "having an
inflammatory component" is meant to designate any condition which
is accompanied locally or temporally with syndromes characteristic
of an inflammatory reaction, such as the induction of certain
cytokines, in particular soluble IL-2R (sIL-2R), IL-6 and IL-8, and
increased levels of inflammatory cells, in particular T-cells and
macrophages, at sites of lesions or around lesions. Such
inflammatory and/or an autoimmune component may form part of the
hypopigmentary disorder or may be in addition thereto.
[0091] The term "accompanied temporally" may mean that the
inflammatory component precedes the hypopigmentary disorder, is
concomitant therewith or follows it.
[0092] The term "autoimmune component" in an organism is meant to
designate any condition which is characterized by a reaction of the
organism's own immune system against the organism itself or tissues
or cells or other components thereof. An example of such a reaction
is the production of auto-antibodies which are antibodies that are
directed at some of an organism's own tissues or cells or other
body components.
[0093] Examples of hypopigmentary disorders are, but not limited
to, albinism, vitiligo, postinflammatory hypopigmentation,
piebaldism, Pityariasis alba, Hypomelanoses, Leukodermas,
hypopigmentation occurring e.g. after externally induced peels,
e.g. chemical peels with phenol, or laser or cryo-surgery of the
skin, Chediak-Higashi syndrome, Hermansky-Pudlak syndrome, the
Angelman and Prader-Willi syndrome. An especially preferred
hypopigmentary disorder of the present invention is vitiligo.
[0094] Examples of hypopigmentary disorders in which T cell
activation and proliferation plays a role are postinflammatory
hypopigmentation and vitiligo, preferably vitiligo.
[0095] Treatment according to the present invention relates to the
complete or partial healing of the hypopigmentary disorder in
mammals, including humans as well as to the stop or slowing-down of
the progression of a hypopigmentary disorder. Also, the compounds
of the present invention are suitable for the prevention of a
hypopigmentary disorder in mammals, including humans.
[0096] Treatment of vitiligo according to the present invention
relates to the complete or partial healing of the disorder
vitiligo; i.e. complete or partial repigmentation of existing white
macules on vitiligo patients, as well as to the stop or
slowing-down of the extension of the white macule areas on vitiligo
patients. Prevention of vitiligo according to the present invention
relates to the prevention of occurrence of vitiligo phenotype in to
date unaffected persons. Preferably, such unaffected persons are
persons with higher risk of vitiligo; i.e. persons with a family
history of vitiligo.
Pharmaceutical Compositions
Pharmaceutically Acceptable Salts
[0097] Examples of pharmaceutically acceptable addition salts
include, without limitation, the non-toxic inorganic and organic
acid addition salts such as the acetate derived from acetic acid,
the aconate derived from aconitic acid, the ascorbate derived from
ascorbic acid, the benzenesulfonate derived from benzensulfonic
acid, the benzoate derived from benzoic acid, the cinnamate derived
from cinnamic acid, the citrate derived from citric acid, the
embonate derived from embonic acid, the enantate derived from
enanthic acid, the formate derived from formic acid, the fumarate
derived from fumaric acid, the glutamate derived from glutamic
acid, the glycolate derived from glycolic acid, the hydrochloride
derived from hydrochloric acid, the hydrobromide derived from
hydrobromic acid, the lactate derived from lactic acid, the maleate
derived from maleic acid, the malonate derived from malonic acid,
the mandelate derived from mandelic acid, the methanesulfonate
derived from methane sulphonic acid, the naphthalene-2-sulphonate
derived from naphtalene-2-sulphonic acid, the nitrate derived from
nitric acid, the perchlorate derived from perchloric acid, the
phosphate derived from phosphoric acid, the phthalate derived from
phthalic acid, the salicylate derived from salicylic acid, the
sorbate derived from sorbic acid, the stearate derived from stearic
acid, the succinate derived from succinic acid, the sulphate
derived from sulphuric acid, the tartrate derived from tartaric
acid, the toluene-p-sulphonate derived from p-toluene sulphonic
acid, and the like. Such salts may be formed by procedures well
known and described in the art.
[0098] Other acids such as oxalic acid, which may not be considered
pharmaceutically acceptable, may be useful in the preparation of
salts useful as intermediates in obtaining a chemical compound of
the invention and its pharmaceutically acceptable acid addition
salt.
[0099] In another embodiment, the compounds of the invention are
used in its free base form according to the present invention.
[0100] Metal salts of a chemical compound of the invention include
alkali metal salts, such as the sodium salt of a chemical compound
of the invention containing a carboxy group.
[0101] The chemical compounds of the invention may be provided in
unsolvated or solvated forms together with a pharmaceutically
acceptable solvents such as water, ethanol, and the like. Solvated
forms may also include hydrated forms such as the monohydrate, the
dihydrate, the hemihydrate, the trihydrate, the tetrahydrate, and
the like. In general, solvated forms are considered equivalent to
unsolvated forms for the purposes of this invention.
Administration and Formulation
[0102] The production of medicaments containing the PDE5 inhibitors
of the invention, its active metabolites or isomers and salts
according to the invention and their application can be performed
according to well-known pharmaceutical methods.
[0103] While the PDE5 inhibitors of the invention useable according
to the invention for use in therapy may be administered in the form
of the raw chemical compound, it is preferred to introduce the
active ingredient, optionally in the form of a physiologically
acceptable salt in a pharmaceutical composition together with one
or more adjuvants, excipients, carriers, buffers, diluents, and/or
other customary pharmaceutical auxiliaries. Such salts of the PDE5
inhibitors of the invention may be anhydrous or solvated.
[0104] In a preferred embodiment, the invention provides
medicaments comprising a compound useable according to the
invention, or a pharmaceutically acceptable salt or derivative
thereof, together with one or more pharmaceutically acceptable
carriers therefor, and, optionally, other therapeutic and/or
prophylactic ingredients. The carrier(s) must be "acceptable" in
the sense of being compatible with the other ingredients of the
formulation and not harmful to the recipient thereof.
[0105] A medicament of the invention may be those suitable for
oral, rectal, bronchial, nasal, topical, buccal, sub-lingual,
transdermal, vaginal or parenteral (including cutaneous,
subcutaneous, intramuscular, intraperitoneal, intravenous,
intraarterial, intracerebral, intraocular injection or infusion)
administration, or those in a form suitable for administration by
inhalation or insufflation, including powders and liquid aerosol
administration, or by sustained release systems. Suitable examples
of sustained release systems include semipermeable matrices of
solid hydrophobic polymers containing the compound of the
invention, which matrices may be in form of shaped articles, e.g.
films or microcapsules.
[0106] The compounds useable according to the invention, together
with a conventional adjuvant, carrier, or diluent, may thus be
placed into the form of medicament and unit dosages thereof. Such
forms include solids, and in particular tablets, filled capsules,
powder and pellet forms, and liquids, in particular aqueous or
non-aqueous solutions, suspensions, emulsions, elixirs, and
capsules filled with the same, all for oral use, suppositories for
rectal administration, and sterile injectable solutions for
parenteral use. Such medicament and unit dosage forms thereof may
comprise conventional ingredients in conventional proportions, with
or without additional active compounds or principles, and such unit
dosage forms may contain any suitable effective amount of the
active ingredient commensurate with the intended daily dosage range
to be employed.
[0107] The compound useable according to the invention can be
administered in a wide variety of oral and parenteral dosage forms.
It will be obvious to those skilled in the art that the following
dosage forms may comprise, as the active component, either a
compounds useable according to the invention or a pharmaceutically
acceptable salt of a compounds useable according to the
invention.
[0108] For preparing a medicament from a compound useable according
to the invention, pharmaceutically acceptable carriers can be
either solid or liquid. Solid form preparations include powders,
tablets, pills, capsules, cachets, suppositories, and dispersible
granules. A solid carrier can be one or more substances which may
also act as diluents, flavouring agents, solubilizers, lubricants,
suspending agents, binders, preservatives, tablet disintegrating
agents, or an encapsulating material.
[0109] In powders, the carrier is a finely divided solid which is
in a mixture with the finely divided active component. In tablets,
the active component is mixed with the carrier having the necessary
binding capacity in suitable proportions and compacted in the shape
and size desired. Suitable carriers are magnesium carbonate,
magnesium stearate, talc, sugar, lactose, pectin, dextrin, starch,
gelatin, tragacanth, methylcellulose, sodium
carboxymethylcellulose, a low melting wax, cocoa butter, and the
like. The term "preparation" is intended to include the formulation
of the active compound with encapsulating material as carrier
providing a capsule in which the active component, with or without
carriers, is surrounded by a carrier, which is thus in association
with it. Similarly, cachets and lozenges are included. Tablets,
powders, capsules, pills, cachets, and lozenges can be used as
solid forms suitable for oral administration.
[0110] For preparing suppositories, a low melting wax, such as a
mixture of fatty acid glyceride or cocoa butter, is first melted
and the active component is dispersed homogeneously therein, as by
stirring. The molten homogenous mixture is then poured into
convenient sized moulds, allowed to cool, and thereby to solidify.
Compositions suitable for vaginal administration may be presented
as pessaries, tampons, creams, gels, pastes, foams or sprays
containing in addition to the active ingredient such carriers as
are known in the art to be appropriate. Liquid preparations include
solutions, suspensions, and emulsions, for example, water or
water-propylene glycol solutions. For example, parenteral injection
liquid preparations can be formulated as solutions in aqueous
polyethylene glycol solution.
[0111] The chemical compound according to the present invention may
thus be formulated for parenteral administration (e.g. by
injection, for example bolus injection or continuous infusion) and
may be presented in unit dose form in ampoules, pre-filled
syringes, small volume infusion or in multi-dose containers with an
added preservative. The compositions may take such forms as
suspensions, solutions, or emulsions in oily or aqueous vehicles,
and may contain formulation agents such as suspending, stabilising
and/or dispersing agents. Alternatively, the active ingredient may
be in powder form, obtained by aseptic isolation of sterile solid
or by lyophilization from solution, for constitution with a
suitable vehicle, e.g. sterile, pyrogen-free water, before use.
[0112] Aqueous solutions suitable for oral use can be prepared by
dissolving the active component in water and adding suitable
colorants, flavours, stabilising and thickening agents, as desired.
Aqueous suspensions suitable for oral use can be made by dispersing
the finely divided active component in water with viscous material,
such as natural or synthetic gums, resins, methylcellulose, sodium
carboxymethylcellulose, or other well known suspending agents.
[0113] Also included are solid form preparations which are intended
to be converted, shortly before use, to liquid form preparations
for oral administration. Such liquid forms include solutions,
suspensions, and emulsions. These preparations may contain, in
addition to the active component, colorants, flavours, stabilisers,
buffers, artificial and natural sweeteners, dispersants,
thickeners, solubilizing agents, and the like.
[0114] In one embodiment of the present invention, the medicament
is applied topically or systemically or via a combination of the
two routes.
[0115] In an especially preferred embodiment of the present
invention the medicament is applied topically. This reduces
possible side effects and limits the necessary treatment to those
areas affected.
[0116] Preferably the medicament is prepared in form of an
ointment, a gel, a plaster, an emulsion, a lotion, a foam, a cream,
a cream of a mixed phase or amphiphilic emulsion system
(oil/water-water/oil mixed phase), a liposome, a transfersome, a
paste or a powder.
[0117] Ointments and creams may, for example, be formulated with an
aqueous or oily base with the addition of suitable thickening
and/or gelling agents. Lotions may be formulated with an aqueous or
oily base and will in general also contain one or more emulsifying
agents, stabilising agents, dispersing agents, suspending agents,
thickening agents, or colouring agents.
[0118] For topical administration, the compounds of the present
invention may be administered in a formulation containing 0.001% to
10% per weight of the compound, preferably between 0.01% to 10% per
weight of the compound, even more preferred between 0.1% and 5% per
weight of the compound.
[0119] Especially preferred are topical formulations of compounds
of the invention, especially of Tadalafil and Sildenafil and salts
and hydrates thereof, especially in an O/W emulsion (oil-in-water
emulsion) or cream. The invention thus also relates to a
composition suitable for topical use, comprising a compound of the
invention, especially selected from Tadalafil and Sildenafil or a
pharmaceutically acceptable salt thereof.
[0120] Compositions suitable for topical administration in the
mouth include lozenges comprising the active agent in a flavoured
base, usually sucrose and acacia or tragacanth; pastilles
comprising the active ingredient in an inert base such as gelatin
and glycerol or sucrose and acacia; and mouthwashes comprising the
active ingredient in a suitable liquid carrier.
[0121] Solutions or suspensions are applied directly to the nasal
cavity by conventional means, for example with a dropper, pipette
or spray. The compositions may be provided in single or multi-dose
form. In the latter case of a dropper or pipette, this may be
achieved by the patient administering an appropriate, predetermined
volume of the solution or suspension. In the case of a spray, this
may be achieved for example by means of a metering atomising spray
pump.
[0122] Administration to the respiratory tract may also be achieved
by means of an aerosol formulation in which the active ingredient
is provided in a pressurised pack with a suitable propellant such
as a chlorofluorocarbon (CFC) for example dichlorodifluoromethane,
trichlorofluoromethane, or dichlorotetrafluoroethane, carbon
dioxide, or other suitable gas. The aerosol may conveniently also
contain a surfactant such as lecithin. The dose of drug may be
controlled by provision of a metered valve.
[0123] Alternatively the active ingredients may be provided in the
form of a dry powder, for example a powder mix of the compound in a
suitable powder base such as lactose, starch, starch derivatives
such as hydroxypropylmethyl cellulose and polyvinylpyrrolidone
(PVP). Conveniently the powder carrier will form a gel in the nasal
cavity The powder composition may be presented in unit dose form
for example in capsules or cartridges of, e.g., gelatin, or blister
packs from which the powder may be administered by means of an
inhaler.
[0124] In compositions intended for administration to the
respiratory tract, including intranasal compositions, the compound
will generally have a small particle size for example of the order
of 5 microns or less. Such a particle size may be obtained by means
known in the art, for example by micronization.
[0125] When desired, compositions adapted to give sustained release
of the active ingredient may be employed.
[0126] The pharmaceutical preparations are preferably in unit
dosage forms. In such form, the preparation is subdivided into unit
doses containing appropriate quantities of the active component.
The unit dosage form can be a packaged preparation, the package
containing discrete quantities of preparation, such as packaged
tablets, capsules, and powders in vials or ampoules. Also, the unit
dosage form can be a capsule, tablet, cachet, or lozenge itself, or
it can be the appropriate number of any of these in packaged form.
Tablets or capsules for oral administration and liquids for
intravenous administration and continuous infusion are preferred
compositions.
[0127] Further details on techniques for formulation and
administration may be found in the latest edition of Remington's
Pharmaceutical Sciences (Maack Publishing Co. Easton, Pa.).
In another aspect the present invention relates to a composition
comprising a PDE 5 inhibitor useable according to the invention or
an isomer thereof, or a pharmaceutically acceptable salt thereof,
and one or more further active ingredients which are known to be
suitable for the treatment and/or prevention of hypopigmentary
disorders, especially vitiligo. Especially preferred active
ingredients which can be used in combination with the compounds of
the invention are Calcineurin inhibitors, for example Cyclosporin
A, Cyclosporin G, Cyclosporin B, Cyclosporin C, Cyclosporin D,
Dihydro-cyclosporin D, Cyclosporin E, Cyclosporin F, Cyclosporin H,
Cyclosporin I, ASM-240, Pimecrolimus, Tacrolimus,
13-Desmethyl-derivatives of Tacrolimus (L-685487), L-683519 and/or
17-Ethyl-derivatives of Tacrolimus, preferably Pimecrolimus,
Tacrolimus, or Cyclosporin A, especially preferably Tacrolimus,
steroid, for example Betamethasone, Betamethasone-17-valerate,
Fluocinolone, Triamcinolone, Triamcinolone acetonide, clobetasol,
clobetasol propionate, halobetasol, hydrocortisone, cortisone,
desonide, Prednisolone, paramethasone, Methylprednisolone,
Dexamethasone, Deflazacort, Vitamin D analogues, especially
calcipotriol, Pseudocatalase, or other active ingredients which
were suggested for vitiligo treatment like levamisole,
Fluorouracil, alpha-MSH, Clofazimine, Thiambutosine BP,
Chloroquine, Penicillamine, Tar, Minoxidil, Inosiplex,
Mechlorethamine, Cyclophosphamide, Anapsos, Antioxidants like
Gingko biloba, Canthaxanthine, beta-carotene, alpha-Tocopherol,
combination of alpha-Tocopherol, ubiquinone, seleno-methionine and
methionine, Pentoxifylline, vitamins and trace elements, like
Vitamin B12, folic acid, vitamin C, vitamin E, copper salts, human
placental extract, khellin and phenylalanine.
[0128] In an especially preferred embodiment, a PDE 5 inhibitor
useable according to the invention or an isomer thereof, or a
pharmaceutically acceptable salt thereof are combined with a
compound selected from the group of Pimecrolimus, Tacrolimus, and
Cyclosporin A. Especially preferred are combinations of a PDE5
inhibitor selected from Tadalafil and Sildenafil or a
pharmaceutically acceptable salt thereof and a compound selected
from the group of Pimecrolimus, Tacrolimus, and Cyclosporin A.
[0129] In another embodiment, the invention relates to the use of
one of the above-mentioned compositions for the manufacture of a
medicament for the treatment and/or prevention of hypopigmentary
disorders, especially vitiligo. The same administration forms as
discussed above for PDE 5 inhibitors useable according to the
invention or an isomer thereof or a pharmaceutically acceptable
salt thereof alone, are suitable for the compositions, especially
the topical application on lesions for treatment, or on unaffected
skin for prevention. In another aspect of the present invention,
the active ingredients are administered together or spatially
and/or temporally separated.
[0130] In another aspect the present invention relates to
treatments for hypopigmentary disorders, especially vitiligo
comprising administration of a medicament containing PDE 5
inhibitors useable according to the invention or an isomer thereof,
or a pharmaceutically acceptable salt thereof alone and
administration of one or more further treatment forms which are
known to be suitable for the treatment and/or prevention of
vitiligo. Preferred treatment forms which can be combined with the
treatment with a medicament containing PDE 5 inhibitors useable
according to the invention or an isomer thereof, or a
pharmaceutically acceptable salt thereof alone, and optionally
other active substances, are PUVA treatment, KUVA treatment,
heliotherapy, climatotherapy, especially at the Dead Sea, Laser
therapy, for example low energy laser therapy, ultrapulse
carbondioxide laser therapy, short pulse carbondioxide laser
therapy or Ruby laser therapy, surgical therapies like minigraft,
suction epidermal grafting, dermo-epidermal grafts, epidermal
suspensions, in vivo cultured epidermis and melanocyte suspensions,
or UVB treatment.
Assays for Testing Subject Compounds
[0131] In general, tests for measuring the effect on hypopigmentary
disorders are described in the prior art. For example, an in vitro
model consisting of keratinocytes and melanocytes may be used. E.g.
the commercially available MelanoDerm Skin Model (MatTek
Corporation, Ashland, Mass.) uses NHEK (normal human derived
keratinocytes)-NHEM (normal human derived melanocytes) co-cultures
(MelanoDerm Skin model) to model the human epidermis taking into
account that melanocytes are dependent on keratinocyte signalling.
NHEKs are cultivated in culture inserts placed on the NHEM
monolayers according to the instructions of the manufacturer
(MatTek Corporation, Ashland, Mass.). NHEMs undergo spontaneously
melanogenesis up to 3 weeks of culturing. Regarding evaluation of
pharmaceutical agents to stimulate skin pigmentation as needed for
treating hypopigmentary disorders, the tissues darken faster than
untreated controls.
[0132] Other in vitro assays for determining the effect of a
subject compound on hypopigmentary disorders are in vitro assays
based on melanin content analysis.
[0133] Melanin content analysis assays are also described in the
prior art.
[0134] For example, treated and control melanocytes are harvested
by trypsinization. Ten percent of the melanocytes are removed and
counted on a Coulter counter. The remaining melanocytes are
centrifuged and the resulting cell pellet is washed in
phosphate-buffered saline pH 7.4 and re-centrifuged. The cell
pellet is then dissolved in 1 ml of 1 M sodium hydroxide. The
optical density of this solution is measured spectrophotometrically
at 405 nm and is compared to synthetic melanin to determine melanin
content per cell. A higher melanin content reflects enhanced
pigmentation.
[0135] Similarly, the assay can be performed as follows: treated
and control melanocytes are harvested by trypsinization, washed
with phosphate-buffered saline (PBS), suspended in 500 .mu.l PBS,
and counted. The cells are then solubilized by adding 500 .mu.l of
10N NaOH and incubating for 30 min at room temperature. Absorbance
at 475 nm is measured and compared with a standard curve for
synthetic melanin.
[0136] Alternatively, the .sup.14C-tyrosine melanin-formation assay
can be used, which measures the radioactive melanin formed when
.sup.14C-tyrosine is converted to the acid-insoluble melanin
biopolymer. For this assay, cell extracts from treated and control
cells are incubated with .sup.14C-tyrosine for 1 hour and absorbed
on filter paper. The filter paper is dried then washed in 0.1 mol/L
hydrochloric acid three times and placed in a scintillation vial
with 5 ml scintillator solution. The radioactivity is counted in
triplicate using the same scintillator counter.
[0137] Alternatively, the effect of a compound on a hypopigmentary
disorder can be determined by measuring tyrosinase activity, which
are well described in the prior art.
[0138] For example, tyrosinase activity of cell culture can be
determined: treated and control melanocytes are incubated with 1.0
.mu.Ci [.sup.3H]tyrosine per ml. 700 .mu.l of 10% trichloroacetic
acid containing 20% charcoal (charcoal solution) is added to the
medium (700 .mu.l), and the mixture is mixed in a vortex for 30 s
and then centrifuged at 10,000 rpm for 10 min. Seven hundred
microliters of the supernatant is transferred into a new tube and
treated twice with the charcoal solution. The radioactivity of the
final supernatant is determined in a liquid scintillation
counter.
[0139] Alternatively, tyrosinase activity can be determined in cell
extracts. For example, treated and control melanocytes are
collected and washed twice with PBS, and then lyzed in 0.1 M sodium
phosphate buffer (pH 6.8) containing 1% Triton X-100. After
determining the protein content in the cell extract, 10 .mu.g of
each extract is incubated in 100 .mu.l of 100 mM sodium phosphate
buffer (pH 6.8) containing 1.0 .mu.Ci [.sup.3H]tyrosine per ml, 5
.mu.g L-dihydroxyphenylalanine, and 1% Triton X-100 for 15 min at
37.degree. C. After adding 900 .mu.l of charcoal solution, the
samples stand for 20 min at 4.degree. C. and then are centrifuged
at 10,000 rpm for 10 min. The supernatants are applied to a 0.2 ml
Dowex-50 column equilibrated in 10% trichloroacetic acid and washed
with 0.5 ml of 10% trichloroacetic acid, after which the
radioactivity of the effluents is determined in the liquid
scintillation counter.
[0140] Also, some animal models of varying predictability and
suitability exist. An evaluation of suitability of various vitiligo
animal models is described in Vitiligo (eds. S. Hann and J. J.
Nordlund, Blackwell Science, Chapter 33: Animal models by L.
Lamoreux and R. E. Boissy)
[0141] For example, the Smyth chicken exhibiting a genetically
inherited form of vitiligo-like depigmentation resulting from the
loss of melanocytes in feathers is discussed as vitiligo model. The
pigmentation phenotype of this animal model appears to involve an
immune response. Also, the so-called vitiligo mouse is described.
In this model no immune component is involved and the disorder is
not polyfactorial; i.e. unlike in humans.
[0142] Vitiligo, for example, is not a simple, one-locus-disease,
and inheritance is not its only cause. Therefore, in the case of
vitiligo, animal models must be used with the knowledge that the
disorder observed in the genetically defective animal will not be
homologous with the disorder of the average human vitiligo patient.
Thus, the study of one animal model, especially if the defect is
caused by one gene locus in the model, need not be more predictive
than an in vitro model.
[0143] None of the aforementioned tests has proved particular
useful on its own when it came to identifying compounds useful in
the treatment and/or prevention of hypopigmentary disorders, given
that not many compounds are known to have a pronounced positive
effect on the onset of hypopigmentary disorders. This shortcoming
of the prior art has now been overcome, in that the present
inventors have found that surprisingly PDE 5 inhibitors useable
according to the invention or an isomer thereof, or a
pharmaceutically acceptable salt thereof, as defined before,
provide for compounds which have a beneficial effect on
hypopigmentary disorders, especially on vitiligo. Therefore,
according to another aspect of the present invention, it provides
for the use of PDE 5 inhibitors useable according to the invention
or an isomer thereof, or a pharmaceutically acceptable salt
thereof, as defined above, in a screening assay for compounds which
are suitable for the treatment and/or prevention of hypopigmentary
disorders. In one embodiment, such screening assay is an
in-vitro-model consisting of a co-culture of keratinocytes and
melanocytes as described above. In another embodiment the screening
assay is an in-vitro-assay based on melanin content analysis, as
described above. In another embodiment, the screening assay is
based on the measurement of tyrosinase activity, as described
above. In yet another embodiment, the screening assay is based on
an animal model, as described above.
[0144] In all these screening assays the PDE 5 inhibitors useable
according to the invention or an isomer thereof, or a
pharmaceutically acceptable salt thereof serve as positive controls
in that they inhibit/prevent the onset of hypopigmentary disorders,
especially vitiligo and the response of the assay system towards
these controls is compared with the response of the assay system
towards a subject compound to be tested.
[0145] FIG. 1 shows the influence of Sildenafil on dendrite
formation in melanocytes in a melanocyte dendrite outgrowth assay
described below. Positive control is IBMX i.e.
3-isobutyl-1-methylxanthin, a compound known to increase melanocyte
dendricity. The dendricity of untreated melanocytes was set as 1 in
each experiment.
EXAMPLES
Example 1
Effect of Sildenafil on Melanocyte Function
[0146] A possibility to test the effect of a compound on melanocyte
function as a measure for pigmentation, the melanocyte dendrite
outgrowth assay can be performed. Vitiligo melanocytes for example
have only stubby dendrites. Increasing dendricity as a prerequisite
for the transfer of the melanosomes from melanocytes to the
surrounding keratinocytes rescues this defect.
[0147] For this assay, cells from a human melanoma cell line
(Mel-Ho) were obtained from DSMZ (Deutsche Sammlung fur
Mikroorganismen and Zellkulturen) and were cultured according to
the protocol provided by DSMZ. In short, after thawing the
melanocytes were cultured in T-75 flasks in melanocyte culture
media (provided by the manufacturer) until they reach 70-80%
confluency. The melanocytes were then trypsinized, transferred into
5-10 new T-75 flasks, and grown again to same confluency as
described above. After this expansion step the melanocytes were
immediately used for the Melanocyte Dendrite Outgrowth Assay or
were frozen for later use.
[0148] For the assay, the melanocytes were seeded in 24 well plates
at a density of 1-5.times.10.sup.4 cells/well. After 24 hours, the
melanocytes were treated with 100 .mu.M IBMX (Sigma-Aldrich) or
different concentrations of Sildenafil and Tadalafil for 24 hours.
IBMX (=3-isobutyl-1-methylxanthin) is known to cause increased
melanocyte dendricity and was used as a positive control. Cells
treated with media only were used as a negative control. Melanocyte
dendrite outgrowth was documented by digital photography (Canon G2
Powershot) after 3, 6 and 24 hours. In addition, melanocyte
dendricity was scored by 3 blinded individuals after 24 hours. The
score ranges from 1 to 4; 1 representing melanocytes with no
dendrites and 4 representing melanocytes with many long and
branched dendrites. The scoring result of 3 individual experiments
performed with Sildenafil is shown in FIG. 1. FIG. 1 shows the
negative control treated with media only, exhibiting a score of 1,
whereas in the positive control, i.e. IBMX-treated cells, the score
reached >3. Surprisingly it was found that also
Sildenafil-treated cells, dendricity was strongly stimulated (score
>3). 10 .mu.M Sildenafil was used to obtain an score of >3,
however also lower concentrations (down to 10 nM) of Sildenafil was
sufficient to induce dendrite formation.
Example 2
Effect of Tadalafil on Melanocyte Function
[0149] The experiment was performed as described in Example 1,
however using Tadalafil as active component.
[0150] The results obtained for Tadalafil were very similar to the
results obtained with Sildenafil.
[0151] It was found that also Tadalafil effectively induces
dendricity in melanocytes which proves good suitability of the
compounds useable according to the invention for treating and/or
preventing hypopigmentary disorders, especially vitiligo.
[0152] In summary, the strongly increased dendricity induced by
Sildenafil and Tadalafil proves good suitability of the compounds
useable according to the invention for treating and/or preventing
hypopigmentary disorders, especially vitiligo.
Example 3
Effect of PDE5 Inhibitors on Pigmentation In Vitro
[0153] In order to test the effect of PDE5 inhibitors on
pigmentation, an in vitro model consisting of keratinocytes and
melanocytes is used, namely the commercially available MelanoDerm
Skin Model (MatTek Corporation, Ashland, Mass.). This model uses
NHEK (normal human derived keratinocytes)-NHEM (normal human
derived melanocytes) co-cultures (MelanoDerm Skin model) to model
the human epidermis taking into account that melanocytes are
dependent on keratinocyte signalling. NHEKs are cultivated in
culture inserts placed on the NHEM monolayers according to the
instructions of the manufacturer (MatTek Corporation, Ashland,
Mass.). NHEMs undergo spontaneously melanogenesis up to 3 weeks of
culturing. Regarding evaluation of pharmaceutical agents to
stimulate skin pigmentation as needed for treating hypopigmentary
disorders, the tissues darken faster than untreated controls. It is
expected that both Sildenafil and Tadalafil induce pigmentation in
that model compared to the negative controls.
* * * * *